A microperfusion needle is a medical instrument having a body with opposed lateral wings which is associated, on one side, with a tubular element and on the other side with a hollow cannula in fluid communication with the tubular element and adapted to be inserted into a vein of a patient to draw blood from him/her or introduce medicaments into the vein.
A fistula needle is a medical instrument having a body with opposed lateral wings which is associated on one side with a hollow cannula adapted to draw blood from the vein of a patient, and on the other side with a tube that carries such blood to a device known as dialyzer which, after purifying the blood, re-injects the blood into the patient through another tube and another fistula needle.
With a (microperfusion or fistula) needle as mentioned above, as an operator removes the cannula from the vein he/she is known to be exposed to injury and contact with the blood of the patient. In view of preventing infection spreading, the body of the aforementioned needle is known to be associated with an elongate protective element having a cavity, and adapted to receive the cannula once it has been removed from the vein of the patient. Therefore an assembly is obtained, which comprises two components, a first component defined by the (microperfusion or fistula) needle, having the body with the wings and the cannula, and a second component defined by the protective element.
In operation, i.e. when the cannula is introduced into the vein, the cannula projects out of the protective element. The entire assembly is moved during such introduction into the vein, by an action on the wings of the first component; as the cannula is removed from the blood vessel, the entire microperfusion needle (or fistula needle) is caused to slide in the cavity of the second component until the cannula is entirely covered thereby, to avoid any accidental contact with the operator.
A number of embodiments of protective elements as mentioned above are known in the art, and usually include a tubular body (defining the aforementioned cavity), which is open at two opposite ends and has lateral slots through which the wings of the first component can move to allow the cannula to fit into the cavity. These lateral slots also comprise specially shaped portions, which are designed to retain the wings of the first component therein, when the entire cannula is inserted in the second component. Thus, when the first component has to be made safe, it will be locked with respect to the second component and the cannula will be safely prevented from being contacted by the operator. One example of these devices is disclosed in EP 2055344 by the Applicant hereof.
Nevertheless, prior art solutions are still affected by the possibility that, when the entire assembly has to be moved, e.g. when the cannula is introduced into the vein, the (microperfusion or fistula) needle of the first component will slide in the second component (the protective element) or anyway a translational movement of the first component relative to the second component will occur, which may cause accidental injury to both the operator and the patient.